1. Field of the Invention
The invention relates to manufacture of semiconductor chips and somewhat more particularly to manufacture of very thin chips from a semiconductor material having at least one privileged cleavage plane whereby individual chips are attained by division of a larger substrate body which is caused to divide with pressure occurring in the surface of the semiconductor material along the cleavage plane.
2. Prior Art
It is desirable to have very thin semiconductor chips available for high frequency components as well as for power components, such as for example, varactors or gallium-arsenide power field-effect transistors. With thin chips, heat dissipation of a component producec on such semiconductor chips is more favorable and/or the intermediate electrical resistance is smaller than with comparatively thicker semiconductor bodies.
Heretofore, thin semiconductor chips have been produced by eroding the inactive or back surface of thicker substrate bodies by polishing or polishing-etching down to a remaining thickness of about 50 .mu.m or less. The resultant substrate body, which was only then considered adequately thin, was then placed on a support and scratched or scored with a diamond tool in such a manner (generally crosswise) that individual chips of a desired size were attained by subsequent breaking along the score lines, just like cutting a glass plate.
With the foregoing prior art technique, the substrate body utilized had a crystal lattice orientation so that the direction of pressure exerted thereon by the diamond tool during scoring was along one of the fracture planes of the semiconductor material.
Although the foregoing technique has been very widely utilized, it cannot be considered optimum because of the high rejection rate associated therewith. Further, often times the active or front surface of a substrate body on which the score line is traced on the back surface, becomes damaged or scratched during the subsequent breaking process. This causes particularly severe damage when details of a semiconductor component or circuit are already present on the front or active side of such substrate body.